Chain-stitch sewing machine



Oct. 19, 1943.

S. ZONIS ETAL I CHAIN-STITCH SEWING MACHINE Filed March 1, 1941 4 Sheets-Sheet l Oct. 1%, 1943. s. ZONIS ETAL CHAIN-STITCH SEWING MACHINE Filed March 1, 1941 4 Sheets-Sheet 2 QQ V Q M Q w 1 a. A w 1 l 4 Q A .NL a mu. m 2 $91 Q a E NM n ii 7/ 2 NR I: .III I I III E MM a mm CL; w a X Oct. 19, 1943. s. ZONIS ETAL CHAIN-STITCH SEWING MACHINE 4 Sheets-Sheet 3 Filed March 1, 1941 a b and 5 neg Z072 Mum;

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CHAIN-STITCH SEWING MACHINE Filed March 1, 1941 4 Sheets-Sheet 4 @Womu Patented Oct. 19, 1943 cnm-srircn SEWING mom Sydney Zonis and Arthur S. Meloy, .In, Stratl'ord,

001111., asslgnors to The Company, Elizabeth,

New Jersey N. J., a corporation of Singer Manufacturing Application March 1, 1941, Serial No. 381,242 10 Claims. 112-201) This invention relates to chain-stitch sewing machines and more particularly to single thread chain-stitch machines having stitch-forming mechanism including-a conventional wing-type rotary looper as complemental to an eye-pointed -needle in enchaining loops of thread. carried through the work by the needle.

In chain-stitch sewing machines of the type above referred to, the rotarylooper casts ofi one loop of thread as the beak of the looper is entering a succeeding loop of thread presented by the needle. The newly seized thread-loop is thereafter expanded by the rotating looper and presentedfor subsequent entrance by the looper while seizing a succeeding thread-loop.

In chain-stitch sewing machines of prior construction, employing the needle-bar or equivalent means as a thread take-up member, the thread required for expansion of the needle-thread loop by the looper is drawn from the previously expanded loop, by reason of the fact that as the take-up rises with the needle it maintains a taut condition of the thread at the needle side of the seized thread-loop. The tortuous path through which the previously expanded thread-loop is shortened to supply thread to the looper gives rise to a condition causing stealing of thread from its supply and results in the formation of loosely set stitches, particularly at higher'speeds of operation of the machine. To obviate this diihcuity, it has been a common practice to employ intermittently acting thread-nippers timed to lock the thread at the supply side of the take-up during expansion of the thread-loop by the looper. While the thread-nippers perform their intended function as above described, they are a limiting factor in operation speeds and do not alleviate the taut thread conditions, which are liable to lead to specificobjects of the invention will be apparent from the following description and claims.

The invention consists in the devices, combinations and arrangements of parts hereinafter described in connection with the accompanying drawings, which illustrate a preferred embodiment of the invention and in which:

Fig. 1 is a vertical longitudinal section, partly in front elevation, of a sewing machine containing the present improvement. Fig. 2 is a horizontal longitudinal section of the bracket-arm of the machine. Fig. 3 is an enlarged longitudinal section of the looper mechanism assembly unit, the section being taken in a plane containing the axes of rotation of the looperand stub-shafts. Fig. 4 is an enlarged vertical section, transversely of the bed-plate, of the lubricant-containing casing housing the looper-shaft driving gearing.

thread breakage during expansion of thread-loops by the looper.

In thread-handling mechanisms of prior chainstitch machines having a wing-type looper, it has also been the practice to employ 'reciprocatory take-up members or arms provided with threadeyes about which the thread is sharply doubled when taking up the thread and setting the stitches, thereby promoting thread breakage at highspeeds of operation of the machine and particularly when employing poorergrades of thread.

It is an object of the present invention to overcome the above noted diiiiculties inherent inprior chain-stitch machines and to provide a take-up mechanism capable of successfully handling any of the commercial threads at extreme high speeds of operation of the machine. Other andmore Fig. 5 is a front end elevation of the machine, with the bed-plate in vertical .section, the takeup guard removed, and the looper in needlethread loop seizing position. Fig. 6 is an enlarged front side elevation ofthe needle and looper, in the loop-seizing position of the looper illustrated in Fig. 5; fragments of the bed-plate, the work supported thereby, and the feed-dog being shown in vertical section. Figs. '7 and 8, 9 and 10, 11 and 12, and 13 and 14, inclusive, are views respectively similar to Figs. 5 and 6, illustrating successively difierent positions of the needle, looper and takeup mechanism during a stitch-forming cycle.

The sewing machine illustrated in the drawings has a frame including a bed-plate I, from one end of which rises the standard 2 of a hollow bracket-arm 3. The bracket-arm 3 terminates at its free end in a head 4 overhanging the bed-plate l adjacent the end thereof opposite the standard 2.

Rotatably Journaled in ball-bearings 5 and 6, provided within the bracket-arm 3, is a horizontally disposed main actuating shaft 1 carrying at one end thereof a combined hand-wheel and belt-pulley 8. At its opposite end. the mainshaft 1 carrie a crank-disk 9 apertured to receive a shouldered crank-pin I i secured to the crank-disk by a screw l I.

Journaled upon the crank-pin III, as by means I of a needle-bearing, is an apertured boss I2 formed at one end of a link I 3. At its other end, the link I3 is pivotally connected to an endwise reciprocatory needle-bar 14 between vertically spaced bearings I5 and It provided for said needle-bar in the bracket-arm head 4. At its lower .end, the needle-bar It carries an eyepointed needle 11.

the bed-plate l.

The main-shaft 1 carries a peripherally grooved belt-pulley 23 connected by a clip-belt 24 to a similar pulley 25 carried by one end of a horizontally disposed bed-shaft 26 performing one rotation for each rotation of the main-shaft 1. One end of the bed-shaft 26 is rotatably journaled in a ball-bearing 21 supported by a lug 28 depending from the bed-plate At its other end, the bed-shaft 26 is Journaled in a bearing-bushing, 29 suitably secured in a horizontally apertured wall 38 of a casing 3| depending from the bed-plate The casing 3| is chambered to provide a lubricant-reservoir 32 into which the bedshaft extends, the bottom wall of said reservoir comprising a closure-plate 33 detachably secured by screws 34 to the lower face of the casing 3|. Upon the end of the bed-shaft 26 is secured a driving spur-gear 35 of which the hub 35 is circumferentially recessed to provide a seat for a lubricant-splasher 36 adapted to dip into a supply of lubricant contained in the reservoir 32.

The spur-gear 35 is in driving engagement, within the reservoir 32, with an intermediate gear-wheel 31 of a looper mechanism assembly unit. The gear-wheel 31 is formed upon or otherwise carried by one end of a horizontal stubshaft 38 and is disposed adjacent an end face of a cylindrical bushing 39. The stub-shaft 38 is rotatably journaled in needle-bearings 40 disposed at the opposite ends of a longitudinal aperture 4| provided in the bushing 39 eccentrically of the longitudinal center line of the bushing. The stubshaft 38 is restrained against endwise movement by a collar 42 suitably secured upon said stubshaft adjacent the end face of the bushing 39 opposite the gear-wheel 31. The stub-shaft 36 is provided with a longitudinal bore 43 extending from the gear end of the stub-shaft to a port adjacent the opposite end of the stub-shaft. The stub shaft 38 is also provided wtih radial oilducts 44 connecting the shaft-bore 43 with the needle-bearings 40. In order to feed lubricant lengthwise of the shaft-bore 43 to said oil-ducts 44, the shaft-bore is preferably provided with a wick 45 protruding slightly from the gear end of the stub-shaft 38 within the reservoir 32.

The gear-wheel 31 is in driving engagement,

6 within the reservoir 32, with a gear-wheel 46 of the same size as that of the gear-wheel 31 and the spur-gear 35. The gear-wheel 46 is disposed ad acent the same end face of the bushing 39 as the gear-wheel 31 and is formed upon, or other- 6 wise carried by, one end of a horizontally disposed looper-shaft 41. The looper-shaft 41 is substantially parallel to the stub-shaft 38 and is rotatably journaled in needle-bearings 48 disposed at the opposite ends of an aperture 49 extending longitudinally of the bushing 39 eccentrically of the longitudinal center line of the bushing. The looper-shaft 41 extends through the bushing 39, and suitably secured upon the looper-shaft 41 at the endthereof opposite the gear-wheel 46 is a looper-shaft confining collar 50. A wing-type rotary looper of conventional form and complemental to the needle H in the formation of single-thread chain-stitches is provided with a shank-pin 5| suitably secured in a longitudinal bore 52 of the looper-shaft 41, thereby closing one end of said bore which extends from the gear end of the looper-shaft. The looper-shaft is also provided with radial oil-ducts 53 connecting the shaft-bore 52 with the needle-bearings 48 of the looper-shaft. Like the stub-shaft 38, the bore of the looper-shaft 41 is preferably provided with a wick 54 protruding from the gear end of the looper-shaft and extending past the oil-ducts 53.

The rotary looper referred to has the usual curved and slender loop-seizing beak 55 formed at the outer end of a loop-expanding body 56 having inwardly divergent side walls and terminating at the rearward side of said body in a transverse notch or loop-detaining throat 51 inclined to the axis of rotation of the looper. Extending rearwardly beyond the throat 51 is a loop-twisting and spreading wing 58 which holds the needle-thread loop in position for subsequent entrance by the beak 55 of the looper.

The looper-mechanism assembly unit above described is removably and adjustably supported in a horizontal opening 59 provided in a wall 60 of the casing 3|; the bushing 39 being secured by a screw 6| in a set position in which the loopershaft 41 is disposed above the level of and in substantially the vertical plane containing the axis of rotation of the bed-shaft 26.

The work is advanced past the stitch-forming mechanism by a feed-dog 62 of the drop-feed type and which may be actuated in any usual or suitable manner. The feed-dog 62 operates through feed-slots 63 provided in a throat-plate 64 suitably secured upon the bed-plate i, said throatplate also having the usual needle-aperture 65.

The thread-handling or take-up mechanism comprises a plurality of thread-engaging devices relatively rotatable about parallel fixed axes. One of these devices consists of a circular takeup disk 66 secured by screws 61 upon a head 68 at the free end of the crank-pin ID; the disk 66 being concentric with the axis of rotation of the main-shaft 1. Disposed in laterally spaced relation to the disk 66 is a thread-confining fiat ring 69 secured to the disk 66 for rotation therewith by a pair of adjacent thread-engaging elements in the form of studs 10 and an auxiliary thread-engaging element or stud 1| spaced approximately from the proximate stud 18; the studs 16 and 1| being preferably radially equidistant, and the stud 1| being disposed in advance of the studs 10 in the direction of rotation thereof. As the thread-engaging studs 10 and 1| are carried by the main-shaft 1, said studs perform one rotation for each complete reciprocation of the needle.

An auxiliary thread-handling device comprises a rotary take-up disk 12 and a rotary threadconfining flat ring 13 held laterally spaced from the disk 12 by a pair of adjacent and radially equidistant thread-engaging elements or studs 14 connecting the disk and ring for unison rotation. The radius of the orbital path of movement of the elements 14 is less than that of the studs 10, 1|, but the direction of rotation thereof is the same. The auxiliary take-up disk 12 has a hub 15 secured by a screw 16 upon one end of a rotary shaft 11 disposed rearwardly of and parallel to the main-shaft 1; said shaft 11 in the present case having its axis of rotation in the horizontal plane containing the axis of rotation of the main-shaft. The shaft 11 is journaled for rotation in ball-bearings 18 provided in the bracket-arm 3 of the machine. At its end opposite to the take-up disk 12, the shaft 11 carries a peripherally grooved belt-pulley. 79 connected by a clip-belt 80 to a similarly grooved pulley 8| carried by the main-shaft I. The pulley 8| is twice the size of the pulley 19, so that the'shaft I1 rotates twice for each rotation of the main-shaft 1. The orbital paths of rotation of the several take-up or thread-engaging elements 10, H and 14 are preferably contained in the same vertical plane, whereby the needlethread may be passed in one motion over thestuds of the respective disks, and the necessity for intervening thread-guides is obviated.

Secured in any suitable manner upon the bracket-arm head 4 is a face-plate 82 formed at its upper edge with a guard-flange 83 extending usual slack-thread controller spring 89 associ ated therewith, said tension-device being of the type' imposing an adjustably uniform tension upon the thread. The thread then passes about the usual presser-bar controlled guide-rod 90 and forwardly over the studs of the two take-up devices to a thread-guide 9| secured to the faceplate 82, the thread being then directed to the needle I1 by a thread-guide 92 attached to the lower bearing l6 of the needle-bar.

The stitch-formation and the handling of the thread by the take-up mechanism is illustrated in successive steps in Figs. 5 to 14, inclusive, of the drawings. As viewed in said figures, the take-up disks 66 and 12, and the looper, rotate in a counter-clockwise direction.

In Figs. 5 and 6 of the drawings, the needle I! has just begun to rise and the beak 55 ofv the looper is entering the needle-thread loop N' formed by the rising needle, and is also about to enter the loop N" of thread previously expanded I engaging position and begins to take up some looper from the slack thread made available by I the take-up elements 10 and 14 during the rising movement of the needle. While the auxiliary take-up element H has taken up slack thread duringthe described major expansion of the thread-loop N, the take-up elements 10 have reby the looper and detained at this time in the throat 51 thereof. Hi and 14 are together giving up thread and thereby rapidly creating slack thread between the take-up and the needle, while the auxiliary rotary take-up element II is at this time clear of the thread. A surplus of slack thread available at this time, in excess of the thread required for expansion of the thread-loop N' seized bythe looper, has the advantage of accommodating variations in thickness of the work and in stitchlengths, without requiring any retiming of the take-up mechanism.

In Figs. 7 and 8 of the drawings, the beak '55 of the looper is shown as advanced to a point at which the looper is about to begin to expand the newly seized thread-loop N, and has freed the previous loop N" from the throat 51 of the looper. The feed-dog 62 is still out of engagement The rotary take-up elements leased the thread N and the take-up elements H have continued to give up slack thread. Therefore, the auxiliary take-up element H has merely'taken up surplus slack thread not required by the looper for. expansion of the thread-loop.

Because of the slack thread available up to this time at the needle side of the thread-loop N for expansion by the looper, the thread-loop N" previously cast ofi by the looper remains dormant during the major'portion of the expansion of the thread-loop N'. This will be readily understood when it is considered that, in order to shorten the thread-loop N" during the initial expansion of the loop N by the looper, it is necessary to draw thread through the loop of the previously set stitch, across the upper face of the work, downwardly through the last formed needle-aperture in the work, and across the comparatively sharp neck of the looper-beak 55. Thus the resistance imposed tothe drawing of thread from the previous loop is substantially greater and the thread will be drawn by the looper from the slack thread supplied by the take-up. I

The resistance imposed .upon the thread,

should it be drawn across the sharper portion of the looper during the initial expansion of the thread-loop, islikely to be sufiicient to cause the take-up to draw thread through the tension device and thereby to steal thread from its supply, thus later resulting in improperly setting the stitches. To obviate this difficulty, it has heretofore been a common practice to employ an intermittent thread-nipper eifective to lock the thread against movement through the tension device when the thread required by the looper for initial expansion of the thread-loop is drawn from the loop of thread previously cast off by the looper. Under these prior conditions,'the neces- I sity for employment-of an intermittent nipper increases with the speed of operation of the ma chine, but the intermittent nipper is itself a speed limiting factor.

By the present provision of thread-handling mechanism which leaves the previously cast off with the work W, and the relatively rotating thread-loop dormant during the major portion of the expansion of the newly seized thread-loop,

the liability of stealing thread from its supply is obviated, whereby the stitches may be properly set and the requirement for employment -of speed-limiting intermittent-nippers is eliminated.

The surplus slack thread provided by the takeup devices having been taken up by the take-up element'H after major expansion of the threadloop N' by the looper, as illustrated in Figs. 9 and 10, the previously cast-01f thread-loop Nf is now very rapidly drawn up to the work as plement the action of the take-up element ll- Immediately thereafter, the front take-up elements also engage and take up thread. The feed of the work W begins, thereby drawing thread, "and the final expansion of the threadloop N by the looper, as illustrated in Figs. 11 and 12, completes the action of drawing up the thread-loop N" and the setting of the stitch. During the drawing up of the thread-loop N", the thread-loop N passes about the wider portion of the looper body 56, thereby minimizing any snubbing action.

It is to be understood, however, that the stitchsetting position of the parts, as illustrated in Figs. 11 and 12 of the drawings, may vary slightly dependent upon the thickness of the work and the length of the stitch. When the thread-loop N has reached maximum expansion as shown in Figs. 11 and 12, the continued effective action of the take-up elements Ill, II and 14 now draws thread through the tensiondevice and from its supply until the take-up elements reach the posi tion illustrated in Figs. 13 and 14. As the stitchsetting position of the take-up elements varies with the requirements of different thicknesses of work and different stitch-lengths, the length of thread drawn from its supply by the take-up elements automatically meets said requirements.

In the movement of the looper beyond the position illustrated in Figs. 11 and 12, the wing 58 engages the inner limb of the thread-loop N and twists said limb outwardly, while the outer limb of the thread-loop slides along the rounded edge of the wing 58 and is thereby deflected inwardly, as shown in Figs. 13 and 14 of the drawings. The thread-loop N is thereby drawn into the throat 51 of the looper and is held spread for subsequent entrance of the looper-beak 55 and in a position permitting the looper to subsequently cast off the loop.

The improved thread-handling mechanism is thus coordinated with a wing-type chain-stitch looper to (1) provide slack thread during the rising movement of the needle and available .to the looper for major expansion of a thread-loop seized thereby from theneedle, thereby obviating stealing of thread from its. supply; (2) take up surplus slack-thread during said major expansion of the thread-loop while automatically accommodating variations in thickness of the work and in stitch lengths, and at the same time preparing a condition conducive thereafter to rapid drawing up of the previous loop; (3) set the stitches uniformly; (4) draw the length of thread from its supply requisite to meet conditions.

While the cast off thread-loop N" is necessarily drawn up very rapidly, the easy wiping action upon the thread of the relatively rotating and spaced take-up elements obviates the thread-snapping action incidental to .employment of prior take-up eyes about which the thread was sharply bent or doubled. Consequently, the present take-up and wing-type looper combination is capable of handling the poorer grades of commercial threads, as well as the better grades. Inasmuch as the take-up elements are rotated about fixed axes, they may be operated at any speeds which the other mechanism of the sewing machine may withstand and, accordingly, the take-up mechanism of the combination can, in no sense, be considered as a speed limiting factor.

Having thus set forth the nature of the invention what we claim herein is:

1. In a single thread chain-stitch sewing machine, the combination with an endwise movable eye-pointed needle, a rotary wing-tyne looper adapted to enchain thread-loops presented thereto by said needle, and means for rotating said looper, of rotary needle-thread take-up means constructed and arranged to give up thread available to the looper at the needle side of a looper-seized thread-loop during expansion of said thread-loop by said looper, and to draw up cast-off loops of thread subsequently to substantial expansion of succeeding thread-loops by said looper, and actuating mechanism for rotating said take-up means.

2. In a single thread chain-stitch sewing machine, the combination with an endwise movable eye-pointed needle, a rotary wing-type looper adapted to enchain thread-loops presented thereto by said needle, and means for rotating said looper, of rotary needle-thread take-up means coordinated with said needle and looper to delay its action to draw up the needle-thread loop cast ofi by the looper until the succeeding thread-loop seized and expanded by said. looper approaches maximum expansion, and means for rotating said take-up means.

3. In a single thread chain-stitch sewing machine, the combination with an endwise movable eye-pointed needle, a rotary wing-type looper adapted to enchain thread-1c lps presented thereto by said needle, and means for rotating said looper, of a plurality of rotary needle-thread take-up elements coordinated with said needle and looper to provide, at the needle side of a looper-seized thread-loop, slack thread available to the looper during the initial expansion of a thread-loop by said looper, and to begin its action to draw up the previously cast off needle-threadloop as the succeeding thread-loop approaches maximum expansion, and means for rotating said take-up elements.

4. In a single thread chain-stitch sewing machine, the combination with an endwise reciprocatory eye-pointed needle, a rotary wing-type looper adapted to enchain thread-loops presented thereto by said needle, and means for rotating said looper, of rotary needle-thread take-up means constructed and arranged to provide slack thread available to said looper during seizure and initial expansion of a thread-loop by said looper; to take up surplus slack thread at the needle side of and during the major portion of the expansion of the newly seized thread-loop while permitting the previously cast-off loop to remain dormant; and to draw up the previously cast-oif thread-loop and to set the stitch during final expansion of said newly seized thread-loop.

.5. In a single thread chain-stitch sewing machine, the combination with an endwise movable eye-pointed needle, a rotary wing-type looper adapted to enchain thread-loops thereto by said needle, and means for rotating said looper, of needle-thread take-up means including a rotary thread-engaging element constructed and arranged to take up surplus slack thread at the needle side of and during a substantial portion of the expansion of a threadpresented,

loop by said looper, while permitting the previously cast-off loop to remain dormant.

6. In a single thread chain-stitch sewing machine, the combination with an endwise movable eye-pointed needle, a rotary wing-type looper adapted to enchain thread-loops presented thereto by said needle, and means for rotating said looper, of relatively rotatable take-up elements coordinated with said needle and looper to provide slack thread available to said looper for expansion of the needle-thread loops, and for drawing up thread-loops cast oft by said looper, and means for relatively rotating said take-up elements.

'7. In a single thread chain-stitch sewing machine, the combination with an endwise movable eye-pointed needle, a rotary wing-type looper adapted to enchain threadloops presented thereto by said needle, and means for rotating said looper, of relatively rotatable take-up devices for controlling the needle-thread during stitch formation, said devices including a thread engaging element coordinated with said needle and looper to take up surplus slack thread at the needle side of and during a substantial portion of the expansion of the thread-loops by said looper.

8. In a single thread chain-stitch sewing machine, the combination with an endwise movable eye-pointed needle, a rotary wing-type looper,

adapted to enchain thread-loops presented thereto by said needle, and means for rotating said looper, of a plurality of needle-thread takeup devices rotatable about spaced and substantially parallel axes, one of said devices including an element coordinated with said needle and looper to take up surplus slack thread at the needle side of and during a substantial portion of the action of the looper to expand needlethread loops seized by said looper.

9. In a single thread chain-stitch sewing machine, the combination with an endwise movable eye-pointed needle, a rotary wing-type looper adapted to enchain thread-loops presented thereto by said needle, and means for rotating said looper, of a plurality of needle-thread takeup devices rotatable at difierent frequencies and constructed and arranged to begin shortening the thread-loop, cast 01f by the looper, as the looper approaches its position of maximum expansion of a succeeding thread-loop, said devices including a thread-engaging element effective to take up surplus slack thread at the needle side of and during a substantial portion of the expansion of a thread-loop by said looper, while permitting the previously cast-oif loop to remain dormant.

10. In a single thread chain-stitch sewing'machine, the combination with a rotary actuating shaft, an endwise reciprocatory eye-pointed needle, connections for imparting one complete reciprocation to said needle for each complete rotation of said shaft, a rotary looper coordinated with said needle to newly seize a loop of needle-thread and to reenter a previously seized and spread loop of needle-thread preparatory to casting ofi the previously seized and spread thread-loop, of rotary needle-thread take-up means coordinated with said needle and looper to leave the cast ofi thread-loop dormant during substantial expansion of the newly seized threadloop, and thereafter to draw up saidcast-off thread-loop during approximately of rotation of said shaft, and actuating mechanism for rotating said take-up means.

SYDNEY ZONIS. ARTHUR S. MELOY, JR. 

